Typewriting machine



Jan. 6', 1942- w. A. GABRIELSON ETAL 2,268,867

TYPEWRITING MAcHiNE Filed June 19, 1940 4 Sheets-Sheet 1 INVENTORSW-A.GABR\ELSON E ct. MOSH ER A'r'r'oRNEY 1942- w. A. GABRIELSON ETAL 2 3TYPEWRITING MACHINE Filed June 19, 1940 4 Sheets-Sheet 2 ATTORNEY Jan.6, 1942- W.,A. GABRIELSON z-z-rm. 3, TYPEWRITING MACHINE Filed June 19,1940 4 Sheets-Sheet 3 Jan. 6, 1942- w. A. GABRlELSO-N E TAL 2,263,367

TYPEWRITING MACHINE Filed Jun 19, 1940 4 Sheets-Sheet 4 INVENTORS W- A.QAB'R ELSON E.G:- MOSl-HER ATTORNEY Patented Jan. 6, 1942 4 UNITED STATTYPYEWRITING. MACHINE 'William A. Gabriel son and Edson GQMosliier,Syracuse, N. Y; assignors to L. *0. Smith &

' Corona Typewriters, Inc.,-"S corporationof New York yraciise, N. Y., a

l A n m 1940,'seria11vol 341,250

' 7 Claims.

The invention relates to improvements in typewriting machines. I

The improvements provide a typewriting ma; chine operable to type witheither of a--plurality of fontsor sets of types each ofwhich fonts orsets requires a letter spacing different from that of the other font orfonts, the letter'spacing for any single font being uniform, and theimprovements also-provide for automatically conditioning the machine forproperly letter-spacing the characters of any of its-several fonts orsets of types upon conditioning of the machinefor use of said font intyping. 1 The improvements also provide means whereby the changes oftype fonts and letter spacing may be effected by depressing andreleasing a single key.

The improvements also provide means whereby the type font andletter-space changes may made at any point in the travel of the platencarriage and with maximum-ease by a supple mental key-controlled meansoperable to back space the carriage a fraction only of'one letter spaceand hold the carriage so back'spaced during font and letter spacechanging operations.

The improvements also provide means for changingthe number of letterspaces per inch by means of a single key which is depressed and releasedto effect eachsuccessive change of letter spacing. 1

The improvements also provide means for effecting space changing byaxial shift of any one of a plurality of axially registered escapementratchet wheels of equal diameter into posi-' tion for cooperationtherewith of the escapement dogs of a single dogrocker having an in-'variable throw, each ratchet wheel having a different number of teeththan the others and being geared to the platen carriage. j

The improvements are particularly useful as a whole in a machine havingtype bars or type carriers each bearing one type character of each of aplurality of fonts or sets of types, and wherein the change of font iseffected by fontchanging means analogous to case changing meansordinarily employed in machines the type carriers or type bars of whichare provided with upper and lower case characters of a type font. As anexample of; the improved type of machine there is shown one wherein eachtype bar bears one of the characters of a font of large capitals and thecorresponding character of a font of small capitals. I r I Otherpurposes and advantages of the invention will appear from the followingdescription of the preferred embodiment of the invention shown in theaccompanying, drawings in which: Fig. 1. is aver-tical mediallongitudinal. sectional [view of the improved machine, approxi mately onthe line l-l ofFig. 7, with the several parts innormal idleposition andthe machine conditioned for typing with a-font of small capitals andwith minimum letter spacing;

Fig. 2 is a fragmentary vertical sectional view on the'line 2-4 of Fig.7; W 4

Figs. 3 and 4 are views similar to Fig. 2 showingjtheposition of theparts upon successive depressions of the font and space changing key,

3 and 4; I

letter-space changing means;

Fig.6 isa detail view on the line 6.6 of Fig. '7 showing Part of theback-spacing and partial back-spacingmeans of the machine;

. Fig. 7- is a fragmentary vertical transverse sectional view of themachine on the line 1-1 of Fig. 1;

Fig. 8 is a fra machine; and

Figs.-9 and 10 are detail views of the backspacing mechanism, showingrespectively the parts in normal idleposition and as they appear at theendofan operating stroke of the backspacing pawl' or dog. I

The improvements are shown embodied in a preferred form thereof inv-aknown L C Smith typewriting machine, only so much of which known machineis shown asis necessary for an understanding of .the improvements;

The machine; isprovided with the usual arcuate set of: type bars I!)pivotally mounted inthe usual way OIIthG usual arcuate type ha segmentI! to strike-rearwardly to-theplaten 12. Each type bar-isoperable asusual by one of the usual series of key actions. 'Each, individual keyaction comprises a key'lever l3 carrying an appropriate'character-keyHand' fulcrumed at its rear end on'the usual fulcrum bar IS on themainframe 16 of the machine. The key levers [3 are returned against theusual stop H on the main frame by the usual return springs l8 an-'chored to the key levers and main-frame. Upon -depression ,-of anycharacter key its associated type'bar is-swung rearwardly to printingposition by the usual sub-lever l 9 of that key action,

which sub-lever is connected as usual v to the associated typebar by alink 20 and to the associated keyilever by a link 2|. The sub-levers I955 are fulcrumed at 22,0n the main frame l6.

saidkey being fully depressed in'each of Figs.

Fig. 5 is a detail top plan view of a part of the gmentaryrear elevationof the v On the printing stroke of each type bar the associatedsub-lever I9 moves rearwardly the usual arcuate universal bar 23 of themachine, said universal bar including a central rearwardly extendingstem 23 connected to the tail or lower end of the usual escapement dogcarrier or dog rocker 24 of the machine to rock the rocker about itspivotal axis 25 on the main framework. The dog rocker and universal barare restored to normal position on the return stroke of any actuatedtype bar by the usual dog rocker return spring 26. The usual dog rockerstops 2! and 28 on the main frame limit the extent of motion of both thedog rocker and universal bar. The dog rocker carries at its upperend;the usual escapement dogs 29 and 3|! for alternate coaction in the knownmanner with the teeth of an escapement wheel to letter-space the usualplaten carriage 3| in which platen I2 is journalled as usual. Thecarriage is mounted as usual on the main frame to travel transversely ofthe machine on suitable ball bearings 32v and is normally urged towardthe left-hand side. of the machine by thev usual escapement spring drum(not shown) on the main frame, connected with the carriage by the usualdraw band (not shown).

The usual feed rack 33- is fixed to the carriage to travel therewith andmeshes with the usual feed pinion 34 fixed on a feed shaft 35. The

feed shaft is journalled in a fixed bearing sleeve 36 on the main frameand is held against axial movement by feed pinion 34 and a fixed collaron the shaft.

In the improved machine the type bars carry, instead of the usual set orfont of upper-case types and usual setor font of lower-case types, a setor font of types 31 such as large capitals requiring one letter spacing,and a set or font of types 33 such as small capitals requiring a lesserextent of letter spacing, the large capitals being located nearest thefree end of the type bars in the machine shown. Each type bar carriestwo types for printing like characters of different ones of said twofonts.

In the improved machine means are provided for conditioning the machinefor typing with either set or font of types and for automaticallyconditioning the escapement to feed the carriage letter space distancesappropriate to the font of type in use.

The type bar segment H is supported onthe main frame to shift up anddown relatively to the platen 2 to condition the machine fortyping witheither font. To this end the segment is supported adjacent each end onthe frame -by ball bearings 39 in suitable races to shift up and downand is al'so'supported to shift up and down by a pair of rock arms 40(Fig. 7) fixed on a rock shaft 4|. Arms 40' are pivoted at 42 to thesegment, and shaft 4| extends transversely of the machine and isjournalled in the main frame. The up and down movements of the segmentare limited by stops 43 and 44 carried by a threaded stem 45 screwedinto the segment. This stem is reciprocable in an aperture 46 in aportion of frame l6 which is engageable by the stops.

Fixedto shaft 4| adjacent the right hand end of the shaft is aforwardly'extending rock arm 41 transversely through which passes ahorizontall-y disposed pin or bolt 48 having a. tight driving fit insaid arm or otherwise held to the arm against movement. Rigidly weldedor otherwise fixed to arm 41 is an angular bracket or extension 49 towhich is anchored the rear end of a This means will now'be' described.

segment lifting coiled spring 50 the front end of which is anchored tothe main frame l6.

Spring 50 is adapted to raise the segment and hold stop 43 engaged withthe main frame, in which position of the segment the font or set oftypes 38 are coactive with the platen at the printing point to print.Shaft 4| and the arms fixed thereto constitute a shift frame for thetype bar segment. By pulling the segment down by rocking shaft 4| inopposition to the pull of spring 50 until the segment stop 44 engagesthe main frame the segment may be positioned for coaction of thefont oftypes 31 with the platen to print. Means are provided for so pullingdown the segment and for latching it down.

A draw link 5| has its upper end loosely pivoted on bolt 48 and engagedin a slot in arm 41 (see Fig. 7) to swing about said bolt in said slot.Changes of font and of letter space extent are effected by operation ofa single font and escapement changing key lever 52 bearing a key 53 andfulcrumed on the fulcrum bar I5 on the main frame. A return spring 54connected to the key lever 52 and main frame l6 normally swings andholds the key lever 52 up against the key lever stop H. The key lever 52is located adjacent the right hand side of the machine and hasprojecting laterally inward therefrom about midway the ends of saidlever a horizontal stud '55 having a reduced intermediate portionconstantly engaged in an up and down extending slot 56 inthe draw link5|. In the position of the parts in Figs. 1, 2 and 7 the stud 55 is atthe bottom of slot 56.

In Fig. 3 key lever 52 is shown pressed down to shift the segment andits shift frame from the position shown in Figs. 1, 2 and 7 to the otheroperative position of the segment in which the large capital types arecoactive with the platen. During the downward movement of the key lever52 and its key 53 it will be obvious that stud 55 has pulled down drawlink 5| until the segment was lowered" and arrested by stop 44. Duringthis downward movement of the segment it will be seen that a pivotedlatch lever 51 has acted on the shift frame just as the segment reachedits lowest position to latch the segment and shift frame against returnmovement by spring 50. The key lever 52 may now return to normalposition upon release of pressure on its key without releasing thislatch. In so doing, the stud 5'5 rises in slot 56 but does not leave theupper end of said slot. On the next depression of the key lever 52 thelatch will be released on the down stroke of the key lever as shown inFig. 4 and on the following up stroke of the key lever 52 the segmentand shift frame and latch 51 will be restored to the position of Figs.'1, 2 and 7. Itwill thus be seen that alternate changes of font areeffected by alternate cycles of operation of key lever 52, each cycle ofoperation of said key lever comprising a down stroke and a return or upstroke of the key lever.

This is accomplished in the following manner. Latch lever 51 is anupstanding lever pivoted about midway its ends on the main frame by apivot 58 to swing fore-and-aft of the machine. A light spring 59anchored to the main frame and the upper arm of latch lever 5'I'normallyurges the said upper arm of the lever 51 rearward. At its rear side,below its upper end, the lever 51 is formed with a downwardly facingshoulder 60. Extending upward from the rear end of shoulder 60 to theupper end of lever 51 is a rear edge portion 6| of said lever. In theposition of the parts'shown in Figs. 1, 2 and '7 the latch out until thesegment reaches its loWer-,

most position, and will then clear bolt 48 and permit shoulder 68 of thelatch to slide over the top of'the bolt and thus lock the segment downas shown in Fig. 3 in which lever 52 is shown fully depressed. On thereturn stroke of this cycle of operation of key lever 52 a latchreleasing dog 62 on the key lever 52 is ineffective to release thelatch. During the down stroke of the next succeeding cycle of operationof the key lever 52 the dog 62 will release the latch 51 as shown inFig. 4, and on the return stroke of this cycle of operation of key lever52 said dog 62 will hold the latch 51 released until bolt 48 moves upbehind edge 6| of the latch, after which said edge will hold the latchout until'the next succeeding cycle of operation of keylever 52.

DOg 62 is pivotally held to the key lever 52 13 which is mounted onshaft to turn therewith and to slide along said shaft. A pin or key 14fixed in the sleeve is slidable in the keyway 68. Axial movement of therigidly connected wheelsis limited in one direction by abutment of onewheel with collar 35 and is limited in the other direction by abutmentof the other wheel with collar 69. The wheels 1| and 12 are of equaldiameter. Wheel 1| has twelve equally spaced teethl coactive with theescapement dogs for feeding the platen carriage twelve letter spaces perinch, while wheel 12 has eight equally spaced teeth coactive' with theescapement dogs to feed the carriage eight letter spaces per inch, inthe machine shown. When the wheels are shifted to their forward limit ofsliding motion only wheel 1| is positioned for coaction therewith of theescapement dogs. When'the wheels are shifted to their rear limit ofsliding motion only the wheel 12 is positioned for coaction therewith ofthe escapement dogs. The axial spacing of by a horizontal pivot 63 andhas a forwardly I extending arm to which and to the key lever 52 isanchored a light spring 64 normally tending to hold the dog positionedas in Figs. 2 and 3 relatively to the key lever in which the other armof the bell-crank shaped dog depends vertically from the key lever. Thependent arm of dog 62 is provided at its rear lower corner with a notch65, and the rear edge of said pendent arm is inclined upward and forwardfrom the notch 65 to provide a cam edge 66.

When key lever 52 is operated through one cycle to shift the segmentdownward and leave it latched down, the dog 62 on the down stroke of thelever moves from the position shown in Fig. 2 to that of Fig. 3 withoutsaid dog engaging a laterally projecting lug 61 formed on the lower endof latch 51 and extending toward the right side of the machine. On thereturn stroke of this cycle of operation of key lever 52, the cam edge66 of dog 62 will ride up past lug 61, the spring 64 permitting the dogto yield as edge 66 rides up across lug 61 and then swinging the dog tonormal position with respect to the key lever so that at the end of thekey return on this cycle of operation the lug 61 will be engaged in thenotch of dog 62. Consequently on the next succeeding cycle of operationof key lever 52 the dog 62 will during the down stroke of the leverthrow out the latch 51 as shown in Fig. 4 and will hold the latch thrownout on the return stroke of said cycle until bolt 48 has risen highenough to engage behind the lower end of edge 6| of the latch, whichedge will thereafter hold out I the latch during the remainder of saidreturn stroke and until key lever 52 is next depressed.

The improved machine is provided with novel escapement means and meansfor automatically setting said escapement means for letter-spacing thecarriage in accordance with the font selected for use by actuation ofkey lever 52, as will now be described. The feed shaft 35 of theescapement extends rearwardly beyond collar 35 and is provided with alongitudinal slot or key-way 68 from said collar to the rear end of theshaft. A removable collar 69 is detachably held on the rear end of shaft35 by a suitable set screw 10. A pair of axially spaced escapementratchet wheel 1| and 12 are fixedly united by a sleeve ill the wheels issuch that when either Wheel is positioned in the field of action of theescapement dogs the other wheel is entirely out of the field of actionof the dogs. I The united wheelsare shifted by an escapement settingtrain operable by font selecting movement of the segment shift frame'ofthe machine. A wheel shifting lever 15 extending transversely of themachine is pivoted about midway its ends on the main frame by a verticalpivot 16. 'At its inner end the lever 15 has a substantially circularhead the periphery of which engages the inner faces of the two unitedescapementwheels, and at its outer end said lever is formed with anupstanding fork in which is engaged a pin or stud 11 extendinghorizontally inward from the pendent side arm of a yoke 18 looselypivoted on a known rock shaft 19 of the known machine in which theimprovement are shown embodied. Rock shaft 19 is journalled on the mainframe; Collars on said shaft prevent axial movement of yoke 18. Yoke 18has a rearwardly extending side arm which is connected by a pendent link8| to an inwardly extending rear crank arm 82 of a fore-and-aftextending crank shaft 83 journalled on the main frame adjacent the righthand side of the machine. An

inwardly extending forward crank arm 84 of said crank shaft is connectedby a pendent link 85 with bolt 48. The lower end of link 85 is pivotedon the bolt 48 between the arm 41 and 'a nut 48 This known mechanismWill of the bolt 01' pin 48. Crank screwed on a reduced threaded innerend portion arm 84 and a collar 86 on shaft 83 hold the shaft againstaxial movement.

The escapement wheel shifting train just described will shift wheel 1|into operative position when the segment is shifted upward, and saidtrain will shift wheel 12 into operative position when the segment isshifted downward. The wheel shifting train will'hold the wheels inwhichever position they are shifted until the segment is again shiftedby the segment shifting means.

'For back spacing the platen carriage a letter space at a time theimproved machine is provided with a back spacing mechanism similar tothat of the known machine before referred to. now be described. A backspacing key 81 is carried by a back spacing key lever 88 fulcrumed onframe member I5 and normally held up against stop member [1 by a returnspring I8 which is anchored to the key lever and to the main frame 16 asin the case of the character key levers. The key lever 88 is locatedadjacent the left hand side of the machine. A bellcrank lever 90fulcrumed at 9| on the main frame has a forwardly extending armconnected by a pendent link 92 with key lever 88 forward of the fulcrumof the key lever, and said bellcrank has a pendent arm connected by arearwardly extending link 93 with a pendent rock arm 94 fixed on a rockshaft 95 journalled in bearings 98 on the main frame. Adjacent its righthand end the shaft 95 has fixed thereto a downwardly-bowedforwardly-extending rock arm 91 the forward end of which is connected byan upwardly extending link 98 to the inwardly r leftwardly extending armof a bellcrank 99 fulcrumed at I00 on a part of the main framework I6.Bellcrank 99 has an upwardly extending arm connected by an inwardly orleftwardly extending link IOI to the pendent arm of the back spacingpawl or dog I02, and said pawl has an inwardly or leftwardly extendingarm provided with a reduced left hand end portion i02 slidably guided ina vertical notch I03 in a part of the main frame. Pawl I02 is fulcrumedat I04 on the upper end of a laterally swingable link I05 which isfulcrumed at its lower end at I06 on the main frame. Pawl I02 is formedwith a cam edge I02 extending downward and rightward from the lowerright hand end edge of extension I 02 of the pawl for coaction with thebottom edge of the notch I93 in the frame. A pair of teeth I0'I areprovided on the upper edge of extension I02 of pawl I02 for coactionwith the teeth of a back spacing ratchet wheel I08 fixed on the forwardend of feed shaft 35 of the carriage escapement in the same verticaltransverse plane of the machine in which the pawl I02 is located. A pawlretracting spring I09 is anchored at its left hand end to the arm I05and at its right hand end to the main framework and normally holds thepawl retracted from wheel I08 as shown in Figs. 8 and 9 with the pawlteeth retracted from the wheel I08 and with a rightwardly facing stopshoulder I02 on the tooth-bearing arm of the pawl engaged with a stoplug I I0 on the frame IS.

The operation of this known back spacing mechanism for back spacing theplaten carriage one letter space for each depression and release of theback spacing key 81 will be briefly described. Upon depression of thekey 81 the pawl I02 will move leftward and its tooth-carrying end willrise to engage its teeth with the teeth of wheel I08. As the pawlcontinues to move from the position of Fig. 9 to that of Fig. 10 it willturn wheel I08 clockwise and thus drive the carriage backward or towardthe right far enough to back space the carriage one letter space ortooth space of either of the wheels II and I2. Before the carriage canbe driven further the cam edge I02 on the pawl rides far enough upwardand leftward on the bottom edge of notch I03 to jam lock wheel I08 asshown in Fig. 10. The use of this known back spacer to back space thecarriage one letter space at a time irrespective of whichof the wheelsII and-I2 is in operative position is feasible because the known backspacer, as is common in the art, is made to drive the carriage backwardmaterially more than one but less than two letter spaces before jamming.Thus a back spacer with the conventional partial overthrow for wheel 1Imay be used to back space wheel I2 also a full letter space at a time.

In the improved machine novel means are mally spaced provided forfacilitating the shifting of the escapement wheels II and 12 and forholding the carriage against leftward movement durin shifting of thewheels, thus making it possible to easily shift the wheels and to dothis at any point in the travel of the carriage. This improved meansincludes utilization of the known back spacing means.

An auxiliary fractional back-spacing key III is carried by an auxiliaryfractional back-spacing key lever II2 provided adjacent the left handside of the machine alongside the main back spacing key lever 88. Saidkey lever H2 is fulcrumed on member I5 and normally held against stop I1by a return spring I8 as in the case of the character key levers I3 ofthe machine. Forward of shaft 95 and parallel thereto a horizontal rockshaft II3 extends transversely of the machine and is journalled inbearings II4 on the main frame. Fixed on shaft II3 near the left handend of the shaft is a forwardly and downward extending tappet .arm II5having at its free end a tappet lug IIG underlying and norbelow the keylever II2 to be engaged by the latter after a substantial downwardmovement of key lever II2 but before said key lever reaches the limit ofits downward movement and prior to jamming of the back space pawl ashereinafter more fully described. Shaft II3 has fixed thereto a pendentrock arm III connected by a rearwardly extending link I I8 to thedownwardly bowed part of the forwardly extending and downwardly bowedarm 91 on shaft 95, the point of pivotal connection of link III! witharm 91 being shown at H9 in Fig. 6. If desired, a supplemental returnspring I20 for the back spacing mechanism may be anchored to the mainframe I6 and to a fixed rock arm I2I extending forward from shaft I I3.

When it is desired to change type fonts and,

escapement ratchet wheels by actuation of key 53 at the right hand sideof the keyboard, the typist may first depress key I II at the left handside of the keyboard and hold key I II depressed until key 53 isdepressed and allowed to return. By so doing the carriage will be backspaced a fraction only of one letter space and held in this partiallyback spaced position during a cycle of operation of key 53. Thisfractional back spacing and holding or locking of the carriage willrelieve the pressure of the normally engaged escapement dog with theengaged tooth of the active escapement wheel and facilitate positioningof a tooth of the other wheel in position for engagement by saidescapement dog. It will also prevent jumping of the. carriage to theleft during a change of escapement wheels.

What we claim is:

1. In a typewriting machine of the kind having a platen and a carriagefor said platen escapement-controlled for letter spacing the platen, thecombination of escapement dogs, an escapement dog carrier vibrative in afixed field, a plurality of escapement wheels geared to the carriage andeach having a different number of differently spaced teeth, a set oftype carriers each carrying as many types of different sets as there areescapement wheels, key-controlled means for selectively actuating thetype carriers, key-controlled means for conditioning the machine fortyping with either set of types and for simultaneously axially shiftingthe escapement wheels to present and maintain a selected one of saidescapement wheels in position for coaction of the escapement dogstherewith, thewheel presented being different for each set of types, andkey-controlled means for holding the carriage against letter feed travelduring actuation of the second-mentioned key-controlled means;

2 In a typewriting machine of the kind having a platen and a carriagefor said platen escapement-controlled for letter spacing the platen, thecombination of escapement dogs, an escapement dog carrier vibrative in afixed field, a plurality of escapement wheels geared to the carriage andeach having a different number of differently spaced teeth, a set oftype carriers each carrying as many types of different sets as there areescapement wheels, key-controlled means for selectively actuating thetype carriers, key-controlled means for conditioning the machine fortyping with either set of types and for also simultaneously axiallyshifting the escapement wheels to present and maintain a given one ofsaid escapement Wheels in position for coaction of the escapement dogstherewith, the wheels presented being different for each set of types,and key-controlled means for fractionally backspacing the carriage andalso holding it so back-- spaced during operation of the secondmentioned key-controlled means.

3. In a typewriting machine of the kind having a platen and a carriagefor said platen escapement-controlled for letter spacing the platen, thecombination of escapement dogs, an escapement dog carrier vibrative in afixed field, a plurality of escapement wheels geared to the carriage andeach having a different number of differently spaced teeth, a set oftype carriers each carrying as many types of different sets as there areescapement wheels, key-controlled means for selectively actuating thetype carriers, and key-controlled means for conditioning the machine fortyping with either set of types and simultaneously axially shifting theescapement wheels to present and maintain a given one of said escapementwheels in position for coaction of the escapement dogs therewith, theWheel presented being difierent for each set of types, and key-operatedmeans operable by depression and holding down of its key to lock thecarriage against letter space movement.

4. In a typewriting machine of the kind having a platen carriage, a dogcarrier vibrative in a fixed field, and escapement dogs on the dogcarrier, the combination of a plurality of axially aligned and spacedescapement wheels geared to the carriage and each having a differentnumber of differently spaced teeth from all others of said Wheels, keycontrolled means for. axially shifting said wheels as a unit to positionone wheel at a time in an operative position for coaction therewith ofthe dogs on said dog carrier to letter space the carriage upon vibrationof the dog carrier, and key-controlled means for fractionally backspacing the operative wheel to relieve the pressure thereof on thenormally engaged escapement dog and for holding the carriage thus backspaced during operation of the first-mentioned key controlled means.

5. In a typewriting machine, the combination of a traveling platencarriage, a feed rack on said carriage, a feed shaft journalled on theframe of the machine and held against axial movement, a feed pinionfixed on said shaft and meshing with said rack, a plurality ofexternally toothed escapement wheels of equal diameter slidably keyed tosaid shaft to turn With the shaft and slide as a unit along said shaft,each wheel having a different number of teeth than the others and theteeth of each wheel being uniformly spaced, an escapement dog carriervibrative in a fixed field, escapement dogs on said carrier, and meansfor sliding the wheels as a unit along said shaft to position eitherwheel for coaction of the escapement dogs therewith to letter space thecarriage, a back spacing ratchet wheel fixed on said shaft, key-operatedmeans coactive with the back-spacing ratchet wheel to back space thecarriage one letter space at a time, and keyoperated means operable onpart of said lastmentioned means to fractionally back space the carriageto facilitate change of escapement wheels and lock the carriage duringchange of escapement wheels.

6. In a typewriting machine, a platen carriage escapement comprising apair of escapement wheels each having a different tooth spacing from theother, an escapement dog carrier vibrative in a fixed field and havingescapement dogs for coaction with one or the other of said escapementwheels, an oppositely movable key, means operable by alternate cycles ofoperation of said key for alternately presenting and holding differentones of said escapement wheels in position for coaction therewith of theescapement dogs, each cycle of operation of said key consisting of amovement of the key in one direction and a movement of said key in theopposite direction, and key-operated means for fractionally back spacingthe carriage and holding it back spaced through said means by manualpressure on the key of said key-operated means.

'7. In a typewriting machine having a shift frame alternately shiftableto either of two positions for conditioning the machine for typing witheither of two sets of types, the combination of a platen carriage, aplaten on the carriage, an escapement dog carrier, escapement dogs onthe carrier, means for vibrating the dog carrier at each printingoperation of the machine, two

escapement wheels geared to the carriage and alternatively axiallyshiftable into position for coaction therewith of the escapement dogs, aconnection between said shift. frame and said escapement wheels for soaxially shifting the wheels when the shift frame is shifted and holdingthem shifted until the shift frame is again shifted, and manuallycontrolled means'for shifting the shift frame from either of itspositions to the other and holding it there until said manuallycontrolled means is again actuated.

WILLIAM A. GABRIELSQN. EDSON G. MOSHIER.

